[Chevypower]

In the older days, they used to do a PAN & SCAN and choose which part of the frame lined up better for 4:3 - it may have been center cut, it may have been the left or right part. (more time and effort went in to it). When 16:9 broadcasts started, they just took an SD center cut of the same signal, so you would miss both edges equally on the 4:3 analog broadcast. This didn't matter too much, because when they started, they would film knowing where the 4:3 "safe zone" markers were. They are on the camera's viewfinder or monitor. Nowadays, I don't think they worry too much about 4:3, it's all done for 16:9. The cinematographers (and photographer's) "rule of thirds" stops most things from getting too close to the edge of the screen anyway. If I haven't made this clear, the source tape is the HD master (16:9) which gets fed to transmission in HD 16:9 and also simultaneously downconverted to SD for analog broadcast, where only the 4:3 center cut is used. No effort put in for that.